1. Field of the Invention
This invention relates to an image display apparatus.
2. Description of the Related Art
Japanese Patent Application Laid-Open No. 2-257553 discloses a technique for controlling the pulse width of the voltage applied to each of the modulation electrodes to compensate for the variation in the amount of the electron beams emitted from plural electron-emitting devices due to the variation of the voltages applied to the electron-emitting devices.
Japanese Patent Application Laid-Open No. 8-248920 (U.S. Pat. No. 5,734,361) discloses an image forming apparatus using electron-emitting devices arranged in simple matrix. This image forming apparatus includes a drive signal generating means for outputting a drive pulse to plural column wirings for driving a cold cathode devices connected to a selected row wiring. This drive signal generating means outputs a drive pulse corrected by a correction value corresponding to each column wiring.
Japanese Patent Application Laid-Open No. 2003-223131 (US 2003/0006976 A1; U.S. Pat. No. 7,079,161), discloses a configuration in which in order to reduce the hardware for calculating the correction value, the row wirings have plural reference positions for which a correction value is determined. The apparatus also discloses the configuration in which the correction values other than those for the reference positions are determined by interpolating the correction values determined for the reference positions. Japanese Patent Application Laid-Open No. 2003-223131 (US 2003/0006976 A1; U.S. Pat. No. 7,079,161) further discloses a method for calculating the voltage drop amount using a degenerate model and an algorithm for calculating the correction value from the voltage drop amount.
In the method disclosed by Japanese Patent Application Laid-Open No. 2003-223131 (US 2003/0006976 A1; U.S. Pat. No. 7,079,161), the voltage drop amount is estimated from the image data before correction and the correction value of the image data is determined based on the voltage drop amount thus estimated. In the case where the shape of the drive pulse changes due to the correction, the voltage drop status changes and the emission current amount may also change. The method disclosed by Japanese Patent Application Laid-Open No. 2003-223131 (US 2003/0006976 A1; U.S. Pat. No. 7,079,161), however, approximately ignores the change in the voltage drop status due to the correction. In the case where this correction method is used for a display panel large in voltage drop amount, therefore, the correction error is so large that the image quality may be deteriorated.